The present invention relates to railcar-mounted warning lights and more particularly to status-indicating assemblies mounted on the wheels of train cars that utilize the rotation of the axle to generate power.
It is known that the lack of lighting on railcars presents a serious safety issue for motorists, especially at uncontrolled rail crossings. The sides of train cars are typically unlit. At night, the train locomotive headlights quickly pass the crossing and drivers of vehicles sometimes do not see the railcars and run into the unlit side of the train, resulting in serious injury or death.
The high cost of monitoring and controlling all rail crossings is prohibitive. It would therefore be advantageous to provide warning lights directly on the railcars. However, lack of electrical service onboard the majority of railcars has presented the greatest difficulty with respect to the installation of warning lights. Gas generators and conventional alternators have been tried, however, bulky installation and safety hazards with respect to sparks from carbon brushes have restricted their use.
U.S. Pat. No. 5,828,135 issued to Barrett is known which describes a wheel-mounted generator used to power electrical braking systems, car lighting and other functions requiring electricity. The generator produces electricity through the relative motion of permanent magnets adjacent to stationary coils positioned about the railcar axle. Barrett has addressed the issue of securing coils about the axle, however, it necessitates complex construction and it""s power producing capability far exceeds that to power a warning light system and it adds significantly to the cost of installation, considering the large number of railcars.
Boyer, in U.S. Pat. No. 4,539,497 discloses a wheel-mounted generator within a toroidal housing for mounting around a vehicle axle. The generator is suitable to provide power to associated signal transmitters responsive to such apparatus as tire pressure sensors on multi-wheel vehicles. A pendulum is journaled about the housing passage through which the axle passes. A ring gear is mounted to the housing and engages a pinion gear on the generator armature shaft when the housing rotates. The ratio of the gears drives the generator at a rate greater than the wheel rotation rate. A magnet is attached to and rotates with the housing. The armature of the generator remains relatively stationary with respect to the magnet due to the resistance of the gears rather than the weight of the pendulum. Gear-driven generators require significant servicing to ensure replacement of worn gears for continued operation.
In U.S. Pat. No. 5,584,561 to Lahos, utilizes a simple combination of two separate components; a magnet attached to the rotating wheel of a bicycle and a solenoid attached to the fixed bicycle frame. The solenoid""s coil is electrically connected to a series of diodes. In operation, the wheel-mounted magnet is repeatedly driven past the solenoid during rotation of the wheel. The magnet""s magnetic field generates an alternating current in the solenoid""s coil which is fed to a diode bridge where the signal is rectified and fed to an electronic signaling device that produces electronic pulses to electroluminescent diodes. Electrical storage devices are provided for ensuring continued lighting even if the wheel is not rotating.
In the Lahos application, the bicycle has a convenient frame and wheel providing consistent spacing, a generally non-hazardous environment and a positive relative rotation for periodic induction of an electrical current.
In the context of a railcar, the fixed frame portion is not necessarily located in convenient proximity to the rotating components and the potentially damaging heavy industrial environment includes impact hazards and a prevalence of spalled metal from rails and other metal debris. In such industrial settings, an exposed magnet quickly accumulates metal debris which can render it unable to produce sufficient magnetic field to induce an electrical current in a passing solenoid coil. In the rare instances in which the bicycle-mounted magnet of Lahos would accumulate metallic debris, the failure is readily detected and then the magnet can also be easily cleaned by the rider.
In contrast to Lahos"" bicycle case, a railway environment is rife with metallic debris which would foul the apparatus of Lahos and, as a train of railcars has few operators, failures are unlikely to be detected in a timely manner. Costs of maintenance would escalate if inductive magnets on all train car wheels required cleaning at each servicing or more frequent servicing to ensure reliable magnetic fields. As well, the need to modify the wheel supports, axles or axle endcaps for installing two separate components would add significantly to the installation costs. One also readily recognizes the inherent delicate nature of the inductive solenoid and magnet arrangement of Lahos and the risk of damage if positioned on the outside of a railcar wheel.
In an earlier attempt to improve the power output of wheel mounted generators, Thomas et al in U.S. Pat. No. 4,539,496 have taught that it is the offset position of the generator from the axis of rotation of the wheel that results in a gear xe2x80x9cstep-upxe2x80x9d of the mechanical driving force of the generator resulting in increased electrical power output.
Further attempts to produce increased amounts of electricity from wheel mounted generators have resulted in the use of multiple sets of coils and magnets, positioned offset the axis of rotation of the wheel, inside a housing. One problem inherent with the offset use of multiple magnet and coil generators is the strength of the attraction of the magnets for the metal core in the coils, which may, if large enough, cause the pendulous mass inside the housing to begin rotating about its axis of suspension, along with the rotating housing, and effectively terminating the objective of generating power.
A number of approaches to prevent co-rotation of the pendulum with the wheel generator housing have been suggested. In recently issued U.S. Pat. No. 6,116,763 to King, an asymmetric weight is attached to the pendulum in much the same way counterweights were used in earlier references for wheel-mounted rotating devices, such as hub odometers. The addition of the counterweight addresses co-rotation caused by frictional drag, but it does not fully address co-rotation caused by the attraction between the magnet and the coil core.
Further, there are other cases in which the rail industry has gone to extraordinary effort to provide indicating apparatus for hot bearings and the like. For instance, it is known to provide hot box detectors adjacent the rails and if the detector spots a hot box (a hot journal or wheel bearings indicating onset of failure) then a signal is sent to a dispatcher who then warns the train operator by radio. Detection of a hot box have conventionally been by infrared detection, based on a measurements taken only as the rail wheel passes a sensor and are thus subject to incorrect readings. Further, the hot box detectors tend only to detect hot boxes near failure, when the temperatures are sufficiently high to ensure detection. Further, sensors in the detectors, such as the bolometer, require a highly stable and accurate high voltage supply. Others, such as pyroelectric cells have a lower power requirement but exhibit a variable response, dependent upon infrared exposure and its strength. If there was an onboard and wheel-powered sensor, then more sensitive data and cumulative readings could be obtained and thus transmit more comprehensive data to a track-side receiver, or to the locomotive.
Clearly, there is a need to provide a reliable, low cost status and warning light system which preferably combines the simplicity and low power requirements of the Lahos system, but is suitable for the rough industrial environment of trains and railcars, prevents co-rotation of the non-rotational elements with the rotational elements, and further meets the need for servicing and safety requirements associated with railcars.
A self-contained power and status-indicating assembly is provided for mounting on the axles of railcars. In a preferred embodiment, a protective housing is mounted for co-rotation with the axle. A bearing and pendulum are mounted within the housing to form a non-rotating structure. An electromagnetic current induction system comprising a solenoid and a magnet is installed at an eccentric pivot between the non-rotating structure and the rotating housing. Low-power devices are electrically connected to the solenoid for the periodic receipt of battery and line-less power. The housing, pendulum and induction system thus form a simple and inexpensive assembly which is protected from contaminants, is virtually maintenance free and is easily retrofitted to railcar axles.
In one preferred embodiment, the low-power status device is a light, such as a super-bright LED so that solenoid operation results in the repeated emission of light. Other embodiments include temperature and vibration sensors which may be combined with status LED""s and infrared or radio transceivers. Radio transceivers, coupled with long storage life batteries, can be used to broadcast a strong and long signal upon detecting the status of a characteristic having a long MTBF.
Therefore, in a broad aspect of the invention, a power generation assembly mounts to the rotating axle of a railcar comprising a rotating structure mounted to the axis of the railcar axle for co-rotation with the axle and a non-rotating structure which is maintained so using an eccentric mounting structure connected to and extending from the non-rotating structure. A bearing rotatably supports the non-rotating structure from the rotating structure. An arm is pivotally connected to the eccentric mounting structure at a position offset the axis of rotation of the axle, thus creating an eccentric axis of rotation. A magnet and a solenoid are mounted to one of either the rotating structure or the non-rotating arm for relative movement and arranged so that the solenoid repeatedly passes through the magnetic field of the magnet as the axle rotates, inducing electrical energy in the solenoid. A low-power consumption device, preferably a light-emitting diode, is connected electrically to the solenoid so that the induced electrical energy causes operation of the device; in the case of the LED, to emit light visible to oncoming motorists and thereby indicating the presence of the railcar. A capacitance circuit can provide continuity of power between induced energy production. Should the non-rotating structure be induced to co-rotate with the rotating structure due to attraction between the magnet and the coil core, the eccentric axis of rotation of the arm causes the magnet and coil to pivot away from one another, thus breaking the attraction and limiting any co-rotation to a small arcuate pendulous motion.
In another preferred embodiment, a low powered device is provided for indicating two or more status conditions via LEDs or RF transceivers. In combination with a hot box detector equipped with a compatible light or RF receiver, railcar status can be directly communicated.
Preferably, a housing is provided for forming a chamber which surrounds the magnet and solenoid for excluding contaminants.
One preferred embodiment provides the housing as the rotating structure. Preferably, the solenoid is mounted to the arm, adding weight to the arms""s gravitational resistance to rotation, a counterweight is attached to the eccentric mounting structure to assist in preventing frictionally induced co-rotation of the housing and the generator, and the magnet is mounted to the housing. In this instance, the status-indicating device rotates, and thus is enclosed within the housing. A lens is provided to enable light emission to be visible from without the housing.
In other embodiments, the solenoid may be mounted to the housing and no restriction is imposed on mounting of the status-indicating device, obviating the need for a lens in the case of LED""s intended for viewing.